Stressed plants produce aspirin-like chemical

September 23, 2008 Researchers at the National Center for Atmospheric Research have found that stressed plants produce an aspirin-like chemical,  methyl salicylate. Methyl salicylate is also known as oil of wintergreen. This semi-volatile plant hormone was detected in the air above the plants in the experiments conducted in a walnut grove near  Davis, California. According to the scientists the chemical may be a sort of immune response that help protect the plants.

Acetylsalicylic acid, commonly called aspirin, had originally come from the bark of Willow trees. It had never been observed to be emitted as a gas. The researchers observed spikes in methyl salicylate after nighttime temperatures dipped low, which suggested the plants were reacting to cold stress. The peaks were higher during a dry period, pointing to combined stress of cold nighttime temperatures and mild drought.

Laboratory observations have shown that numerous plants produce methyl salicylate, but this is the first time the phenomenon has been observed in nature. Previous studies have shown that plants being eaten by animals produce chemicals that can be sensed by other plants. A study conducted in 1997 found that methyl salicylate is produced by tobacco plants inoculated with tobacco mosaic virus. Emitting methyl salicylate may be a means for the plants to warn other plants about a threat.

The finding may help to more readily identify plants under stress by monitoring for the airborne distress signal.